System and method for speed indication through transmit power control commands

ABSTRACT

Speed indication device ( 100 ) for determining a speed indication signal ( 410 ) indicating a speed of a wireless mobile telecommunication device ( 14 ) relative to the speed indication device ( 100 ), wherein the speed indication device ( 100 ) determines the speed indication signal ( 410 ) from a sequence of transmit power control commands sent by the wireless mobile telecommunication device ( 14 ) to an access point ( 12 ) in a wireless telecommunication device ( 14 ) to an access point ( 12 ) in a wireless telecommunication network for controlling, in use, a transmit power of a radio signal transmitted by the access point ( 12 ) to the wireless mobile telecommunication device ( 14 ). If the relative speed is found to be above a threshold, the speed may be calculated using a measurement of the Doppler frequency.

FIELD OF THE INVENTION

The present invention relates to a speed indication device as defined inthe preamble of claim 1. Moreover, the present invention relates to atelecommunication access point encompassing such a speed indicationdevice. Further, the present invention relates to a method fordetermining a speed indication by such a speed indication device.

PRIOR ART

In WO 01/41335 a relative velocity estimation using TPC commands isdisclosed. In a system having an transmitter and a receiver thatcommunicate over a radio channel and in which signal transmission powerof the transmitter is adjusted to compensate for fading dips in thechannel, the Rayleigh fading rate of the radio channel, and thus therelative velocity between transmitter and receiver are estimated byeffectively observing the adjustments or fluctuations in signaltransmission power or amplitude of the transmitter. This is done byobserving TPC (Transmission Power Control) commands that cause thetransmitter to adjust its signal transmission power to combat Rayleighfading, i.e., fading dips.

Further, such a speed indication device is known from EP 0 913 953:“CDMA Reception apparatus which measures Doppler frequency of CDMAsignals”.

UMTS (Universal Mobile Telecommunication System) systems using W-CDMA(Wide-band Code Division Multiple Access) typically have multiplefrequencies. These frequencies can be used in several ways, but onetypical way is by building a so called hierarchical cell structure(HCS).

In HCS two or three layers of cells exist, each on its own frequency.The cells within the structure may be of different size. In one suchlayer, all cells have similar size. Typically, in a layer withsmall-sized cells, these cells are aimed at providing access to thesystem for mobile devices, such as mobile phones or other wirelesselectronic devices as personal computers and personal digital assistants(PCs, PDAs) etc. of low(er)-mobility users, while in another layer withlarge cells, these large cells provide access to mobile devices ofhigh(er)-mobility users. For example, pedestrian speed users are on thesmall cells, and motorway speed users are on the large cells. With athree layer HCS a medium speed (with medium-sized cells) can also beidentified.

Such a hierarchical cell structure has the advantage of a high capacity,through the small cells for low-mobility users, with limited number ofhand-overs, through the large cells for the high-mobility users. Inorder to operate a cell structure using such a scheme, information onthe speed of each mobile user within the HCS must be available.

In the speed indication device of the prior art, as disclosed in EP 0913 953, the speed of a mobile device relative to the access point(Radio Base Station) of the cell to which the mobile device isassociated is determined by measuring a Doppler effect in the signalreceived from the mobile device.

As described also in the 3rd Generation Partnership Project (3GPP)specification “UE Radio Transmission and Reception (FDD)”, TechnicalSpecification TS 25.01, speed measurement is through Dopplermeasurements.

The Doppler shift of a radio frequency (RF) signal is equal to the speedat which it is moving towards or from the measurement point, withincreased or decreased frequency, respectively.

Assuming a substantially circular cell shape, the Doppler effect willonly reveal the speed of a mobile device in a radial direction relativeto the access point of the cell. When a mobile device is moving inanother direction only the speed resolved in the radial direction ismeasured and hence a lower speed than the actual speed will be measured.

The HCS scheme may misinterpret (and underestimate) the speed of amobile device and the time the mobile device may actually be within acell for slow-moving users. Thus, for example, a prediction regardinghand-over of users to adjacent cells (or another HCS layer) may beinaccurate, which disadvantageously may affect the user-load within theHCS layers and cells.

In addition, this type of speed measurement by Doppler frequency relieson a very accurate knowledge of the centre frequency of both transmitterand receiver. An error of 200 Hz (at 2 GHz) introduces an error of 30m/s=8.3 km/h. 3GPP TS 25.01 specifies ±0.1 ppm (parts per million) whichcorresponds to a Doppler shift of 200 Hz.

Alternatively, a method to estimate changes in user-load within the HCScells is known that applies the counting of the number of hand-oversthat each mobile device within the HCS network initiates per timeinstance. However, this method is very rough. On average, hand-oversonly occur once every 10 seconds. When some events need to be filteredin order to get a reliable result, several minutes may pass, in whichmany events may happen, which reduces the interest of the information(e.g., change of speed, start/stop of a call, different coverageconditions, . . . ).

As a further alternative, a mobile device may be equipped with a GlobalPositioning System (GPS) to determine the speed of the mobile device.This method requires additional hardware at each mobile, whichdisadvantageously increases the cost of such a mobile device. Moreover,it requires the GPS system to be available within the (full) HCSnetwork. For various reasons, this may not be the case.

SUMMARY OF THE PRESENT INVENTION

It is an object of the present invention to provide a speed indicationdevice for determining the speed of a mobile device within atelecommunication network that is more accurate than speed indicationdevices from the prior art.

To obtain these and further objects, the present invention relates to aspeed indication device as defined in the preamble of claim 1,characterised in that

-   -   the speed indication device determines the speed indication        signal from a sequence of transmit power control commands sent        by the wireless mobile telecommunication device to an access        point in a wireless telecommunication network for controlling,        in use, a transmit power of a radio signal transmitted by the        access point to the wireless mobile telecommunication device and    -   in that        the speed indication device comprises:    -   a memory for storing the sequence of transmit power control        commands:    -   a logical filter circuit for determining a radio signal strength        minimum in the radio signal at a location of the mobile        telecommunication device by detecting if a predetermined number        of consecutive transmit power control commands from the sequence        of transmit power control commands each comprise either an ‘up’        or a ‘down’ transmit power control command.

The speed indication device according to the present invention thusdetermines the speed of a mobile device by comparing the tendency of asuccessive series of TPC data received from the mobile device.Advantageously, the information obtained from the TPC data can providean estimation of the actual speed of the mobile device, which is moreaccurate than the estimate provided by speed indication devices from theprior art.

Moreover, the present invention relates to a telecommunication accesspoint comprising a speed indication device as described above.

Furthermore, the present invention relates to a method for a speedindication device, as described above, characterised in that

-   -   the method comprises determining the speed indication signal        from a sequence of transmit power control commands sent by the        wireless mobile telecommunication device to an access point in a        wireless telecommunication network for controlling, in use, a        transmit power of a radio signal transmitted by the access point        to the wireless mobile telecommunication device, and        determining a radio signal strength minimum in said radio signal        at a location of said mobile telecommunication device (14) by        detecting if a predetermined number of consecutive transmit        power control commands from said sequence of transmit power        control commands each comprise either an ‘up’ or a ‘down’        transmit Rower control command.

BRIEF DESCRIPTION OF THE DRAWINGS

Below, the invention will be explained with reference to some drawings,which are intended for illustration purposes only and not to limit thescope of protection as defined in the accompanying claims.

FIG. 1 shows schematically a wireless network in which a speedindication device according to the present invention is implemented;

FIG. 2 shows schematically a relation between a strength of a radiosignal in a radio environment and TPC data sent by a mobile device to anaccess point when traversing that radio environment having the signalstrength as shown;

FIG. 3 shows schematically a speed indication device in accordance withthe present invention;

FIG. 4 shows schematically a further embodiment of the speed indicationdevice in accordance with the present invention;

FIG. 5 shows schematically a speed information control loop functiondiagram for an access point in accordance with the present invention;

FIG. 6 shows schematically a further embodiment of a speed informationcontrol loop device for an access point in accordance with the presentinvention.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows schematically a wireless telecommunication network in whichthe speed indication device according to the present invention isimplemented.

The wireless telecommunication network 1 is configured according to theHierarchical Cell Structure concept. The network 1 comprises a pluralityof layers (i.e., at least two), each layer having one frequency andcomprising a plurality of (circular) cells. For reasons of clarity, onlya first and second layer 2, 4 are shown, with cells 5, 6 and cells 7, 8associated with first layer 2 and second layer 4, respectively. Each ofthe cells 5, 6, 7, 8 is set-up by a respective access point (Radio BaseSystem) 9, 10, 11, 12. Within each (frequency) layer 2, 4 the size ofthe cells is constant, e.g., in one layer the cell radius is 1 km, inthe other layer the cell radius is 100 m. As an example, in the firstlayer 2 a first and second larger cell 5, 6 are defined in the HCS. Inthe second layer 4 a first and a second smaller cell 7, 8 are defined.Within the cells a plurality of mobile telecommunication devices, suchas mobile telephones, are each associated with one of the cells 5, 6, 7,8 in a way known to persons skilled in the art. The description will nowfurther be given with reference to one such mobile telephone 14.However, it is to be understood that the invention is equally applicablefor any other kind of mobile telecommunication device, as indicatedearlier.

As described above, mobile telephone 14 may move around within thenetwork 1 with varying speed. While maintaining a dedicated channel, themobile telephone 14 may leave one cell and enter another. This processof hand-over involves the dissociation with the former cell andassociation with the latter (as known by persons skilled in the art).During hand-over the user-load on each cell and the occupancy of thebandwidth will change for both cells. This may affect the throughputwithin the network.

While the mobile telephone 14 is within one cell, it monitors the signalstrength of signals received from the access point to which it isassociated. By sending Transmit Power Control (TPC) commands to theaccess point 9, 10, 11, 12 of the respective cell 5, 6, 7, 8, the mobiletelephone can request from the access point to adapt its transmit powerin such a way that at any location within the cell 5, 6, 7, 8, themobile telephone will receive the signals from the respective accesspoint 9, 10, 11, 12 with a sufficient signal strength. Normally, themobile telephone will sent TPC commands that request the access point toincrease its transmit power by a certain amount (e.g. a ‘1’ TPC command)or to decrease it (e.g. a ‘0’ TPC command), in order to obtain asufficient reception signal strength.

FIG. 2 shows schematically a relation between a strength of a radiosignal in a radio environment and TPC data sent by a mobile telephone toan access point when traversing that radio environment having the signalstrength as shown.

In the present invention the observation is followed that the distancebetween power minima in a fading radio environment has a fixed typicaldistance of λ/2, where λ is the wavelength of the radio signal.

In FIG. 2, the radio signal strength I_(RSS) is plotted vertically as afunction of the distance X of the mobile telephone to a respectiveaccess point in a radio network (solid line). The location'sco-ordinates are plotted schematically in the horizontal direction inFIG. 2.

The TPC data sent by a mobile device traversing the radio networkfollowing the given radio signal strength I_(RSS) is shown by a sequenceof bits (0 or 1), with ‘1’ denoting an increase of the observed radiosignal strength, and ‘0’ denoting a decrease.

The transmission power of the mobile telephone 14 traversing the radionetwork following the given radio signal strength as controlled by theaccess point 12 is depicted by the dashed stepwise function.

When the fading of the radio signal is at a maximum, the required powerto meet the wanted signal-to-interference-ratio (SIR) target is more orless constant, so at that instant the TPC data received by the accesspoint 12 from the mobile telephone 14 will contain zeros and ones in amore or less alternating way.

However, when the mobile device is moving it may go from a minimum to amaximum in the radio signal strength and visa versa, and severalsuccessive equal TPC data will be sent by the mobile telephone 14 whenthe observed radio signal strength I_(RSS) is changing. In the TPC datasent by the mobile device (a TPC data sequence), examples of equalsuccessive TPC data are illustrated by underlining the respective TPCdata in the sequence of bits.

Within a access point according to the present invention a speedindication device is present for analyzing the tendency of the TPC datasequence received from the mobile telephone 14. By observing thetendency of the TPC data sequence received from the mobile telephone 14the speed indication device can determine information concerning thespeed of the mobile device relative to the maximum and minimum receptionsignal strength in the radio environment. The speed indication devicedetermines a speed indication signal from the sequence of TPC commandssent by the mobile telephone 14 to the access point 12 for controlling,in use, the transmit power of a radio signal transmitted by the accesspoint 12 to the mobile telephone 14.

FIG. 3 shows schematically a speed indication device 100 in accordancewith the present invention.

The tendency of a TPC data sequence for traversing a minimum of radiosignal strength while maintaining a dedicated channel is analyzed by aspeed indication device 100 that compares if successive TPC datacomprise equal values (i.e., ‘0’ or ‘1’). In an embodiment, the speedindication device 100 of the present invention comprises a delay linememory 110, a logical filter circuit 120, and a signal filter device130.

The delay line memory 110 comprises a plurality of memory cells of whichin this example five consecutive cells n−1, n, n+1, n+2, n+3 are shown.The logical filter circuit 120 comprises basic logical devices: a firstAND gate 121, a second AND gate 122, an OR gate 123, a first EXOR gate124, a second EXOR gate 125, and an INV gate 126.

In the logical filter circuit 120 the output of first AND gate 121 isconnected to a first input of first EXOR gate 124, the output of OR gate123 is connected to a second input of first EXOR gate 124, the output offirst EXOR gate 124 is further connected to the input of INV gate 126,the output of INV gate 126 is further connected to a first input ofsecond AND gate 122, and the output of second EXOR gate 125 is connectedto a second input of second AND gate 122. The output of second AND gate122 is further connected to the input of signal filter device 130.

The delay line memory cells n−1, n, n+1, n+2, n+3 are connected to thelogical circuit 120. Delay line memory cell n−1 is connected to a firstinput of second EXOR gate 125. Delay line memory cell n is connected toa second input of second EXOR gate 125, to a first input of OR gate 123,and to a first input of first AND gate 121. Delay line memory cell n+1is connected to a second input of OR gate 123, and to a second input offirst AND gate 121. Delay line memory cell n+2 is connected to a thirdinput of OR gate 123, and to a third input of first AND gate 121. Delayline memory cell n+3 is connected to a fourth input of OR gate 123, andto a fourth input of first AND gate 121.

The delay line memory cells n−1, n, n+1, n+2, n+3 receive TPC data asinput, in which successive data are entered into the respectivesuccessive delay line memory cells. Since the delay line memory 110typically comprises a plurality of memory cells, the actual connectionof delay line memory cells n−1, n, n+1, n+2, n+3, in the delay linememory 110 with the logical filter circuit 120 is made by e.g. anaddress decoder (not shown) or in any other way as known to personsskilled in the art. TPC commands received by the access point enter thespeed indication device 100 at TPC command input 105.

The incoming TPC commands are compared with their predecessor(s). It isnoted that various alternatives exist to do the comparison. FIG. 3 showsone exemplary approach of identifying bursts. A burst is a plurality ofconsecutive TPC commands. A burst indicating a minimum of the receptionsignal strength is defined here as at least four equal TPC commands(i.e., ‘1111’). It is noted that another number of equal TPC commandsmay also be used to identify a burst indicating a minimum of thereception signal strength.

When all values (n through n+3) are equal, the first ‘AND’ 121 and the‘OR’ 123 function result in the same value. The first ‘EXOR’ function124 provides a ‘0’ when both values are equal, i.e., the burst containsall the same commands. This result is inverted by INV function 126,resulting in a ‘1’ when all TPC commands are equal, and in ‘0’ when atleast one TPC command differs from the three other ones.

The second ‘EXOR’ function 125 is to check the start of a burst of TPCdata that indicate a minimum of the reception signal strength. The startof the burst is when the TPC commands n and n−1 are not equal. Bothresults are combined through the second ‘AND’ function 122 and finallyfiltered in signal filter device 130.

Signal filter device 130 has the function for determining a runningaverage of the burst rate (as it's output). This filter should typicallyhave a time constant of one to a few seconds. (1 second=1500 samples).It is observed that bursts of equal TPC commands will occur morefrequently at higher speed of the mobile telephone 14, since thereception signal strength will then vary more frequently while themobile telephone 14 traverses a cell.

The resulting output of the signal filter device 130 will be called theTPC speed indication in the rest of the description.

FIG. 4 shows schematically a further embodiment of the speed indicationdevice in accordance with the present invention.

It is noted that in a further embodiment of the speed indication device100, the speed indication device 100 is enhanced in the following way.In FIG. 4, entities with the same reference number as used in thepreceding figures, refer to the same entities. In FIG. 4, between thesecond AND gate 122 and the signal filter device 130 a small burstchecking device 135 is added that checks if the currently identifiedburst has the same signed TPC speed indication as in the previous burst,which obviously does not indicate the traversing of a cell as displayedby the relation between a strength of a radio signal in a radioenvironment and TPC data sent by a mobile telephone to an access pointwhen traversing that radio environment as shown in FIG. 2. If successivebursts have the same signed TPC speed indication, the burst checkingdevice 135 discards the last burst, else the burst is fed into thesignal filter device 130. By this enhancement actual variation in signalstrength of the transmitted signal (i.e., temporary dips and peaks) isobserved by the speed indication device 100, instead of only observingflanks of the transmitted signal.

FIG. 5 shows schematically a speed information control loop functiondiagram for an access point in accordance with the present invention.

In the diagram a mobile phone 14 and an access point 12 are shown. Theaccess point 12 comprise a Doppler frequency measurement device 200, adown link power control (DLPC) device 300, a speed indication deviceaccording to the present invention 100, and a speed information controldevice 400. The access point is shown to comprise the Doppler frequencymeasurement device 200, the DLPC device 300, the speed indication device100, and the speed information control device 400 as separate devices.It is to be understood that such devices may also be implemented in oneprocessor or in a plurality of processors.

In use, the mobile phone 14 is communicating to the access point by aradio link RL. The DLPC device 300 is receiving TPC data by TPC commandlink 310 from the mobile phone 14. TPC command link 310 is alsoconnected to speed indication device 100 as TPC command input 105.

Speed indication device 100 is connected to speed information controldevice 400 by an output comprising a speed indication signal 410.

Doppler frequency measurement device 200 is receives a radio signal 210from the mobile phone 14 via radio link RL.

Further, Doppler frequency measurement device 200 is connected to speedinformation control device 400 by an output comprising Dopplermeasurement signal 220.

The speed information control device 400 receives speed indicationsignal 410 and Doppler measurement signal 220 and has an outputcomprising a speed estimation signal 440, which can be used further bythe access point.

As described above, within a cell of the telecommunication network,mobile phone 14 and the access point 12 maintain radio link RL duringtheir association. While maintaining this radio link RL the mobile phone14 controls the transmission power of the access point 12 through thedown link power control (DLPC) device 300. The transmission power iscontrolled in such a way that the quality of the signal, received by themobile phone 14, is just sufficient The DLPC device 300 performs thiscontrol by observing the quality of the reception, indicated by TPCcommand link 310 which provides an input sequence comprising ‘up/down’signals. When the observed quality is over the required quality, a‘down’ command is sent to the access point 12; when the observed qualityis under the required quality an ‘up’ command is sent to the accesspoint 12. (‘Up ’ and ‘Down’ commands are denoted by a ‘I’ and ‘0’ TPCbit, respectively, as shown in FIG. 2).

Further, the Doppler frequency measurement device 200 determines thespeed of the mobile phone 14 by comparison of a received carrierfrequency with an expected value of the carrier frequency (at zerospeed). The received carrier frequency is changed relative to thecarrier frequency at zero speed due to the Doppler effect, which will beexplained below in more detail.

In the present invention, the information on the speed of the mobiletelephone 14 can be used in a few different ways.

In a first embodiment, the information on the speed of the mobiletelephone 14 is determined by speed info control device 400 from onlythe TPC speed indication signal 410 generated by the speed indicationdevice 100 according to the present invention.

The speed estimation signal 440 output by the speed info control device400 is derived from the speed indication signal 410.

In a second embodiment, the information on the speed of the mobiletelephone 14 is determined by combining Doppler speed measurement asdone by Doppler frequency measurement device 200 and TPC speedindication signal 410 generated by the speed indication device 100.

In the Doppler speed measurement the Doppler frequency measurementdevice 200 compares the received carrier frequency of the receivedsignal with an expected value (of the carrier frequency at zero speed).The difference in frequency is proportional to the speed of the mobilephone 14 to or from the access point 12. The observed speed is:

$v = {\frac{f_{D}}{f_{c}} \cdot c}$

-   -   where f_(D) is the measured Doppler frequency, f_(c) is the        carrier frequency (e.g., 2 GHz) and c is the speed of light (3        10⁸ m/s).

The observed frequency is on average 2/90 times the real speed due tothe fact that any movement to or from the access point 12 is notobserved.

Generally, the Doppler measurement signal 220 shows a more accuratespeed value at high speeds, while the TPC speed indication signal 410shows a more accurate speed value at low speeds. So, in this secondembodiment, it is provided that when the Doppler measurement by Dopplermeasurement device 200 shows a speed less than a predefined threshold,the TPC speed indication signal 410 is used by speed indication controldevice 400, while at speeds above this predefined threshold the Dopplerinformation signal 220 will be used.

In a third embodiment the information on the speed of the mobiletelephone 14 is determined by using both Doppler speed measurementsignal 220 and speed indication signal 410, in combination with a tuningstep at low speed.

FIG. 6 shows schematically a third embodiment of a speed informationcontrol loop device 400 for an access point in accordance with thepresent invention. In FIG. 6, entities with the same reference number asused in the preceding figures, refer to the same entities. Speedinformation control device 400 comprises a speed tuning device 420.Speed tuning device 420 comprises an input for Doppler measurementsignal 220, an input for TPC speed indication signal 410 and an output426 for further determination of speed estimation signal 440 in speedinformation control device 400. Further, the speed tuning device 420comprises memory 425 for storing speed-related information.

The speed tuning device 420 may be implemented as a processor, a logiccontrol circuit or in software or in any other way known to thoseskilled in the art.

The basic strategy is similar to that of the second embodiment.

The memory 425 of speed tuning device comprises a lookup table whichprovides speed-related information in relation to the obtained tuningvalue 450. The speed tuning device 420 reads the value of the Dopplermeasurement signal 220 and compares this value with a predeterminedthreshold value Vth related to a switch 421.

If the Doppler measurement signal 220 shows a Doppler-related speed lessthan the predetermined threshold Vth, the speed estimation signal 440determined by speed information control device 400 is based on the TPCspeed indication signal 410 in the following way.

When the measured Doppler-related speed is low (less than thepredetermined threshold Vth), the switch 421 is in position A (<Vth) andthe speed tuning device 420 divides the value from the Dopplermeasurement signal 220 by the value from the TPC speed indication signal410 in block 422. The result of the division is filtered in filter 427with a long time constant in the speed tuning device 420 to provide aprogressing time-averaged tuning value 450.

The memory 425 of speed tuning device comprises a lookup table whichprovides speed-related information 429 in relation to the obtainedtuning value 450.

Typically, the tuning value 450 may be used by the speed tuning device420 to retrieve in block 428 a speed-related information 424 relating tothe obtained tuning value 450 from memory 425. The speed tuning deviceoutputs this speed-related information 424 as output 426 for furtherdetermination of speed estimation signal 440 in speed informationcontrol device 400.

At a Doppler-related speed above the predefined threshold Vth, theDoppler measurement signal 220 is used as input for speed tuning device420. Switch 421 is in position B (≧Vth).

When the measured Doppler-related speed is high (above the predeterminedthreshold Vth, comparison made at switch 421) speed estimation signal440 determined by speed information control device 400 is based on theTPC speed indication signal 410 in the following way.

The speed tuning device 420 divides the value from the Dopplermeasurement signal 220 by the value from the TPC speed indication signal410 in block 422 to obtain the tuning value 450 which is then filteredin filter 427 by a long time constant to obtain a progressingtime-averaged tuning value 450. The speed tuning device 420 thenmultiplies in block 423 the value from the TPC speed indication signal410 with the progressing time-averaged tuning value 450 to obtain atuned Doppler measurement signal 221. Next, the speed tuning devicepasses the tuned Doppler measurement signal 221 as output 426 to thespeed information control device 400 for further processing to obtain aspeed estimation signal 440.

Thus by determining an information on the speed of the mobile telephone14 (i.e. speed-related information 424 or tuned Doppler measurementsignal 221), the speed estimation value signal 440 is time-averaged andscaled relative to tuning value 450. Also, by applying the tuning value450, which takes into account the relative accuracy of the Dopplermeasurement signal 220 and the TPC speed indication signal 410 independence of the speed of the mobile telephone 14, a more accurateestimation of the speed estimation signal 440 can be obtained.

It is noted that in speed tuning device 400 both the division and themultiplication operations may be done in hardware or in software.

1. An apparatus for determining a speed indication signal indicating aspeed of a wireless mobile telecommunication device relative to saidapparatus, wherein said apparatus determines said speed indicationsignal from a sequence of transmit power control commands sent by saidwireless mobile telecommunication device to an access point in awireless telecommunication network for controlling, in use, a transmitpower of a radio signal transmitted by said access point to saidwireless mobile telecommunication device, wherein said apparatuscomprises: a memory for storing said sequence of transmit power controlcommands; a logical filter circuit for determining a radio signalstrength minimum in said radio signal at a location of said mobiletelecommunication device by detecting if a predetermined number ofconsecutive transmit power control commands from said sequence oftransmit power control commands each comprise either an ‘up’ or ‘down’transmit power control command; a speed information control device forproviding a speed estimation signal for said wireless mobiletelecommunication device; and a Doppler frequency measurement device fordetermining a Doppler speed signal for said wireless mobiletelecommunication device, said apparatus being adapted to provide saidspeed estimation signal in dependence on said speed indication signalfor speeds of said wireless mobile telecommunication device below apredetermined threshold and on said Doppler speed signal for speedsabove said predetermined threshhold; wherein said speed informationcontrol device comprises a speed tuning device, said speed tuning deviceoperative to perform the steps of: determining a tuning value, saidtuning value being a division of said Doppler speed signal over saidspeed-indication signal, said tuning value being filtered with along-time constant; and providing, in dependence of a predeterminedthreshold (V_(th)), for determining of said speed estimation signal:speed-related information, in dependence of said tuning value, at speedsbelow said predetermined threshold (V_(th)); and a tuned Dopplermeasurement signal at speeds above said predetermined threshold(V_(th)), said tuned Doppler measurement signal being said Dopplermeasurement signal multiplied by said tuning value.
 2. A method fordetermining a speed indication signal indicating a speed of a wirelessmobile telecommunication device relative to a stationary wireless accesspoint, said method comprising the steps of: determining said speedindication signal from a sequence of transmit power control commandssent by said wireless mobile telecommunication device to said accesspoint for controlling, in use, a transmit power of a radio signaltransmitted by said access point to said wireless mobiletelecommunication device, wherein said step of determining said speedindication comprises the steps of: storing information related to atleast a portion of said sequence of transmit power control commands;and, determining a radio signal strength minimum in said radio signal ata location of said mobile telecommunication device by detecting if apredetermined number of consecutive transmit power control commands fromsaid sequence of transmit power control commands each comprise either an‘up’ or ‘down’ transmit power control command; determining a Dopplerspeed signal for said wireless mobile telecommunication device;providing said speed estimation signal in dependence on said speedindication signal for speeds of said wireless mobile telecommunicationdevice below a predetermined threshold and on said Doppler speed signalfor speeds above said predetermined threshold; determining a tuningvalue for a speed information control device, said tuning value being adivision of said Doppler speed signal over said speed-indication signal,said tuning value being filtered with a long-time constant; and,providing, in dependence of a predetermined threshold (V_(th)), fordetermining of said speed estimation signal: speed-related information,in dependence of said tuning value, at speeds below said predeterminedthreshold (V_(th)); and, a tuned Doppler measurement signal at speedsabove said predetermined threshold (V_(th)), said tuned Dopplermeasurement signal being said Doppler measurement signal multiplied bysaid tuning value.